Reactions of acetylenes with noble metal carbonyl halides. Part 11. Synthesis of [Pt{CMeC(H)COOMe}(CO)Cl]via polynuclear platinum carbonyls. X-Ray crystal structure determination of the σ-alkenyl platinum complex [N(PPh3)2][Pt{CMeC(H)CO2Me}(CO)Cl2]
Abstract
The polynuclear derivative [{Pt(CO)2}n] reacts, in chloroform solution, with H[Pt(CO)Cl3] and MeCCCO2Me to give [Cl(CO)[graphic omitted]t(CO)Cl](2) and [[graphic omitted]OMe}(CO)Cl](3). Compound (3) reacts with PPh3 to give [Pt{CMeC(H)CO2Me}(PPh3)2Cl](7a), while with chloride ions it is transformed into the anionic complex [Pt{CMeC(H)CO2Me}(CO)Cl2]–(4). A multinuclear n.m.r. study on a series of derivatives is reported. The crystal and molecular structure of [N(PPh3)2][Pt{CMeC(H)CO2Me}(CO)Cl2](4a) has been determined from three-dimensional X-ray data. The complex crystallizes in the monoclinic space group Pc, with two formula units in a unit cell of dimensions a= 9.378(2), b= 14.362(3), c= 14.760(4)Å, and β= 100.10(5)°. The structure was determined by Patterson and Fourier methods and refined by least-squares methods to R= 0.0268 from 3 212 independent reflections with I > 3σ(I). The platinum atom has the expected square-planar co-ordination; relevant bond lengths are Pt–C(sp2) 2.016(7), Pt–C(sp) 1.836(9), Pt–Cl (trans to the alkene) 2.404(2), and Pt–Cl (trans to CO) 2.313(2), while the CC bond distance is 1.32(1)Å. The plane of the olefinic moiety is rotated by 65.6(2)° with respect to the co-ordination plane of the metal atom giving a short intramolecular separation of 3.163(7)Å between Pt and the oxygen of the carboxylate carbonyl group.